title: Central hypothyroidism and its replacement have a significant influence on cardiovascular risk factors in adult hypopituitary patients.
abstract: BACKGROUND
  Thyroid dysfunction may have detrimental effects on patient outcomes. Few studies have assessed this issue in patients with secondary hypothyroidism.
  
  
  OBJECTIVE
  Our objective was to test the hypothesis that thyroid hormone status has an impact on cardiovascular risk factors in adult patients with hypopituitarism.
  
  
  METHODS
  This was a retrospective observational study (1993-2012) at a tertiary referral university hospital.
  
  
  METHODS
  All GH-deficient patients starting GH replacement (1993-2009) with measured free T4 (fT4) (n = 208). Baseline fT4 defined patients as TSH-sufficient and TSH-deficient (further divided into tertiles according to baseline fT4; first tertile had lowest fT4).
  
  
  METHODS
  Anthropometric (body mass index [BMI], waist circumference, total fat (fat mass) and lean body mass [LBM]) and biochemical (lipids and fasting plasma glucose) data were collected at baseline and a median 4.1 years after commencement of GH.
  
  
  RESULTS
  At baseline, fT4 was negatively associated with BMI and waist circumference, but positively with high-density lipoprotein, independent of age, gender, and IGF-I (SD score). Only first-tertile TSH-deficient patients had higher BMI (P = .02), fat mass (P = .03), total cholesterol (P = .05), triglycerides (P < .01), and waist circumference (P = .01), and lower high-density lipoprotein cholesterol (P = .03) as compared with TSH-sufficient patients. At follow-up, IGF-I, LBM, and plasma glucose had increased in all subgroups (P < .01). The change in fT4 (ΔfT4) (follow-up - baseline) was negatively correlated to ΔBMI, ΔLBM, Δtotal cholesterol, and Δlow-density lipoprotein cholesterol (all P < .05, adjusted for ΔIGF-I and ΔGH and hydrocortisone dose). The negative correlation to Δtotal cholesterol and Δlow-density lipoprotein cholesterol persisted only in first-tertile TSH-deficient patients.
  
  
  CONCLUSIONS
  This single-center study over a 20-year period has strengthened the importance of improved awareness of thyroid status and optimal thyroid replacement of hypopituitary patients to reduce cardiovascular risks in hypopituitary patients.
authors.affiliation: Department of Medical Endocrinology, PE2131, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. klose@rh.dk
authors.forename: M
authors.initials: M
authors.lastname: Klose
authors.forename: D
authors.initials: D
authors.lastname: Marina
authors.forename: M-L
authors.initials: ML
authors.lastname: Hartoft-Nielsen
authors.forename: O
authors.initials: O
authors.lastname: Klefter
authors.forename: V
authors.initials: V
authors.lastname: Gavan
authors.forename: L
authors.initials: L
authors.lastname: Hilsted
authors.forename: A K
authors.initials: AK
authors.lastname: Rasmussen
authors.forename: U
authors.initials: U
authors.lastname: Feldt-Rasmussen
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose; D001823:Body Composition; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology*; D005260:Female; D020249:Hormone Replacement Therapy; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D007018:Hypopituitarism / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D007037:Hypothyroidism / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use*; D014280:Triglycerides / Q000097:blood; D055105:Waist Circumference
chemical_list: D001786:Blood Glucose; D014280:Triglycerides; D019382:Human Growth Hormone; D013974:Thyroxine